H.E.C. Robinson. Dardanelles, Sea of Marmara, Bosporus This Australian-made map of the Gallipoli Peninsula and the Dardanelles Strait depicts the problems inherent in Churchill's plan to attack Constantinople (now Istanbul). The extensive minefields in the narrow waterway were covered by artillery, making it difficult for British minesweepers to operate. Amphibious operations were hampered by the rugged terrain on the peninsula. The map also shows the sites of the landings by British, Australian, and New Zealand troops, as well as the places where British and French ships were sunk.